I would agree with the above replies.  Many used Insights will have the Autoswath and Multi-product unlocks.  You would want/need the Autoswath unlock for the planting situation.  It may be helpful in other situations as well.

Multi-product is needed any time two products are being monitored/controlled/logged at the same time.  If you wish to do split-planter, this is considered a multi-product situation and the unlock would be required.

I would recomend looking for a used unit with both unlocks as this will be probably be cheaper than buying one without and unlocking later.

There are different ways of laying out the various modules.  If you are replacing a Raven 440 or the like for NH3 or spraying, the Raven adapter cable may be a good choice. 

All the Insight wiring/modules would be compatible with the Integra, Versa and Edge displays.  The Edge and Versa may not allow all the combinations of equipment that the Insight and Integra can but the layout is the same.

We have some used Insights at this time.